Codes and the Crown
by Trinity Everett
Summary: Summer is a time to relax and rest easy, and in Kate Beckett's case, help her daughter save an imaginary kingdom. - Caskett, Future!Fic.
1. Chapter 1

**Codes and the Crown**

 **Chapter One**

* * *

It's both a blessing and a cause for some concern that the loft is almost silent when she slips inside. With three kids, a dog, and a husband like Castle, her home is _never_ quiet. At least not before midnight, and even then, she might wonder what's happening.

"Hey," she calls, allowing her bag to land on the floor with a quiet thud as she shrugs out of her coat and rolls her head on her shoulders. Her day had been insane. "I'm home. Anybody here?"

It is possible that Castle took everyone out for the evening – maybe some late playtime in the park to tire the little ones out, or a run to grab ice cream, or both – but usually their adventures are accompanied by a text to try to entice her to meet them at their destination. Her phone hasn't buzzed once since she left the precinct, not for personal reasons anyway.

"Rick?" she tries again, listening for any sort of response. After a moment, she hears the faint jingle of Branko's collar and relaxes; they're here. Somewhere.

Rick's appears at the top of the stairs, his clothes beyond damp and a giggling boy under each arm. "Hey! Sorry, sorry. Bath time ran long. Monsters coming your way."

He releases the twins one at a time, giving Reece the chance to descend the stairs halfway before turning Jake loose on the world.

"Hi Mama!" Reece calls, happy as ever.

"Mama!" Jake adds.

They're not anywhere near quiet, but she doesn't shush them, instead holding out her arms to catch her sons and press kisses into their pear-scented hair. They're a handful, her boys, but still her heart calms at their wiggling, eager hugs.

"Hi babies," she murmurs, smearing kisses over their smooth cheeks. "Did you have a good day with Daddy and Lily?"

They nod, jabbering over each other in their haste to give her a run-down of their day. Kate does her best to filter their voices, catching that Jake went on the big boy swings while Reece made a fortress in the sandbox, and the four of them had a picnic in the park that resulted in Branko stealing half of Lily's chips. The mooch.

And speaking of Lily and Branko…

"Where is Lily?" she asks once the boys have calmed (somewhat, at least), hefting a twin on each hip, ignoring her tired body's complaint at the motion. "Did she fall asleep already?"

"Ah, not quite," Rick says, reemerging from the top floor with a pile of towels larger than necessary for a simple bath. Kate narrows her eyes; they better not have tried to make another submersible without her. "I mean, she might be asleep, but she was at my desk when I took PB and J upstairs. Branko's with her," he adds over his shoulder, disappearing into the laundry room.

Well, that explains why she hadn't been greeted at the door. Branislav is every bit the protector his name suggests he should be; he never leaves the kids' sides if he can help it, going so far as to sleep in the upstairs hallway between their rooms at night.

Kate nods, swaying with the boys. She'll see what her daughter is up to momentarily, but first she lifts an eyebrow at her husband when he returns.

"Forget something?" she teases, puckering slightly.

Rick huffs, stepping closer, his hands lifting to cup her cheeks. "No, just wasn't interested in a drive-by kiss to say hello."

She leans into him, allowing him to seal his mouth over hers, his lips firm without being demanding. Her breath stutters and her muscles loosen, the urgency of the day fading away with his kiss.

"Hi," she breathes when he releases her lips, resting her cheek in the cradle of his hand.

"Hi," he echoes. "Now, wasn't that better?"

"Much," she admits, thinking back to the barely-there thing she'd had to settle for on her way out the door this morning. This is definitely better.

"Good." He sneaks another kiss in before releasing her, twisting his lips into a crazy grimace at the boys when they put up a fuss about the affection.

Kate scoffs, dipping her head and nuzzling Jake's neck first, then Reece's. Her boys squirm, nearly pitching out of her arms, only to right themselves at the last second. "My kisses aren't gross, goofballs. Neither are Daddy's."

Rick chuckles, leaning in to blow raspberries on their cheeks. "Okay, Monsters, let Mommy go see your sister and we'll get our reading nest ready."

She grins. "I've been waiting for our reading nest all day. How many books do we get tonight?"

"Free!" the boys cheer together, looking triumphant.

"A Reece book, a Jakey book, an' a Lily book," Reece adds.

"Three," she repeats, nodding in understanding. "One for each of my babies. Good thinking."

She gets three eager nods in return. One is accompanied by wiggled eyebrows, and she has to smother a laugh; Rick is no doubt expecting the boys to go down before the first story is finished. She's not convinced – and after barely seeing them today, she's not so sure she wants them to sleep immediately, either – but she won't dash his hopes.

Instead, she lowers the boys to their feet, skimming her hands over their damp hair as they take off toward the couch and the pile of blankets and pillows they've already amassed.

"You said Lily's in the office?" she asks stepping into her husband's space before he can retreat to wrangle their sons. Her hands skim his sides, avoiding the wet patches of his shirt, settling against his back.

"Yeah," Rick breathes, pulling her into a loose embrace. "I think she needed some quiet time after the crazy day we had." Off her look, he explains, "She had her headphones on when I checked on her last. She'll be glad to see you, though."

Kate nods, resting her cheek on his shoulder, breathing him in. "It's hard being the only girl with you three lunatics around," she remarks, offhand, teasing. His muttered 'hey' makes her smile widen.

"I'll go get her into pajamas so we can read," she adds, giving him a gentle squeeze. Rick hums in agreement but doesn't relinquish his hold on her just yet. He's clearly in need of a break too, so Kate presses her lips to his shirt, giving him a moment to breathe. "And then later, you and me, wine and a bath?"

He exhales at the thought, his mouth touching her brow. "That sounds like perfection, Kate."

"Good. Because I've been imagining it all day." She disengages after a moment, rubbing his back once more before making her way to the office.

She stops short of crossing the threshold, frozen by the concentration she sees on her daughter's face. Just as Castle had said, Lily is seated at his desk, bright pink headphones covering her ears, her dark head bent over a book and a pencil in her hand. Kate smiles, spotting Branko flopped at her side. The dog lifts his head when Kate leans against the bookshelf, but doesn't get up or alert Lily to her presence. It gives Kate the opportunity to watch her daughter, noting how her girl's brow scrunches in consternation and her mouth works to form the word she has in mind.

It's only a pause, because ten seconds later, a triumphant smile spreads across Lily's face – so like her father when he breaks through his writer's block – and her pencil picks up speed again. Whatever she's doing, she's certainly intent on the task.

Kate can't help but wonder what's held her attention this long, long enough for the three biggest kids in the world to have bath time and then some. Not homework, obviously, but it seems like Lily's treating it with the same level of importance.

"Hey, little flower," she calls, careful not to startle her daughter when Lily finally lifts her head and drops the pencil. The girl's eyes flare wide, but she doesn't jump or seem bothered by her intrusion.

"Mom! You're home!" Lily chirps, peeling her headphones from her ears and pushing back from her father's desk. Branko stands with her, ready for their next move.

Kate smiles, nodding. "I am home. Sorry I was gone so long today," she says as she leaves her bookshelf perch, moving to circle her daughter's shoulders and pull her into a hug.

Lily's arms band around her waist, her cheek landing on Kate's belly. "It's okay. It was _hot_ today."

Humming, Kate brushes a gentle hand through her daughter's hair, lowering her fingers to the nape of Lily's neck. "I bet it was. It looked hot from my office. Does that mean you guys got popsicles?"

Her daughter giggles, nodding against her blouse. "I had a green one. And then Daddy gave me a blue one when the boys weren't looking," she confesses, lifting her head, her eyes sparkling.

"Your favorites," Kate whispers, dropping her forehead to rest against Lily's, eager to be a part of the secret. The girl in her arms giggles again, nodding.

"So good," Lily hums, swaying with her. "Daddy said it was big sister priv'lege."

Kate grins, surrendering to the urge to squeeze her daughter tightly. It's easier when school is in session, when Lily and the boys are occupied during the day, but during the summer she's forever torn between needing to do her job and wanting to be at home with her kids to watch them explore their world, to witness everything they get to experience for the first time.

"Daddy's right," she says, rubbing noses with her daughter. "And speaking of the boys, Daddy, Jakey, and Reece are getting the nest ready. Go put on your PJs and we'll read with them?"

Her firstborn nods, dropping her arms and turning back to the desk. "'Kay, Momma. I just need to do one thing first."

Kate watches Lily take her journal between careful hands and move to the bookshelf behind her desk. Her daughter squats, tucking the notebook between an antique miniature globe and a novel she barely remembers owning. Maybe one of her father's Reader's Digest novels, she muses, noting the rich navy leather binding. It's on the tip of her tongue to ask what Lily's up to, but she reminds herself to let it be. It could be a gift, it could be a project she saw at the library, it could just be doodles or actual journaling; either way, Lily will tell her in her own time if she needs to know.

"Okay, ready," her girl breathes, pushing her bangs off her forehead.

"Ready," Kate echoes on a smile, motioning for girl and dog to go ahead, following Lily from the office without another glance back.

As expected, and much to Castle's chagrin, the boys don't go down so easily, squirming and chattering through most of the first two books they read. It's only when Rick opens the third book – Lily's choice – and begins to read about a modern-day princess who turns the tables on every fairy tale and heroically rescues the prince that they settle down. Reece dozes off first, his cheek pressed to Kate's chest, and Jake follows soon after, his little feet poking into her side.

Not Lily, though. Kate watches her daughter's eyes light up as the story progresses, even as her cheek mashes harder against Castle's shirt. The girl is enthralled, swept away by the tale, by the gentle cadence of her father's voice.

Enamored as Lily is with the story, they read far longer than they usually do, breaking their tradition of leaving some for the next night.

"That's so cool," Lily whispers at the completion of the book, looking up at Rick with tired eyes. "Daddy, that was _so_ cool."

Rick smiles, stroking a hand down her back. "It is. The way she cracked the code and figured out where the prince had been taken was so smart."

Lily nods. "She found the right key in the book, the cipher. If she hadn't had that, it woulda been a lot harder."

Castle answers her nod, dusting a kiss across her forehead. "That's right," he praises, cuddling the girl closer. "You picked a good book tonight, Sprout."

Lily yawns into Castle's chest, tucking her hands under her chin. "Thanks Daddy. We started it in school, but we didn't get to finish. And then it was summer."

"Yeah?" Rick asks, lowering his chin to catch Lily's eyes. "I'm glad you brought it home from the library then."

"Me too," she says. "I really liked it. I wanna buy it."

Rick nods, squeezing their daughter. "We'll get it then, because I did, too. Can I tell you a secret?" he asks, glancing in Kate's direction before returning his attention to the girl in his arms. Lily nods, eager to hear what he's about to divulge to her. "The princess reminded me of you and mommy."

Lily beams, twisting to share her excitement with Kate.

"Really?"

"Uh huh. You're beautiful and tall," Castle says, easing Lily back onto his chest, his hand slipping over her hair. "But more importantly, you're smart and brave. You don't back down when things get tough. And," he adds, winking in Kate's direction, "you save the prince all the time."

Affection tugs at her heart, making her wish she could reach for him; princess or prince, he knows they save each other and always have.

"I never saved the prince," Lily murmurs, her eyelids drooping. "Mommy has, but not me."

Rick's lips brush her forehead. "Trust me, Sprout. You have, too."

Kate swallows hard, remembering the difficulty of the months following their shooting, when they were hurting and miserable, and it was often the reminder of the life – the damn near medical miracle, according to her doctors – she carried within her that brought them out of the haze of self-pity and frustration when they couldn't do it for themselves.

"Daddy's right, baby," she says, locking eyes with her husband. "You have. So many times."

Her daughter's lips curve against Rick's shirt. "'Kay Momma. I believe you."

Castle chuckles, thumbing the soft curve of Lily's ear. "Believe Mommy and not me, I see how it is."

Kate grins as Lily giggles, managing to wiggle her foot in the blanket nest and nudge his thigh with her toe. "It's a princess thing, babe. We get each other."

His lips lift in return, the smile more adoring than anything else. Whether it's for her or for Lily, or a more abstract happiness, she's not sure, but it fills her up anyway and she presses her toes into his leg again.

"Once she's out," Beckett says, her voice barely more than a hum, "let's take them up and then come back down and get that bath going."

Her husband's smile widens as he understands her deeper meaning. Having time with their children is wonderful, but it's been a long day and she's ready to have him close as well. Just him.

"Done," he rumbles, giving Lily another few minutes to drift off before he stands with her in his arms and makes the trek up the stairs.


	2. Chapter 2

**Codes and the Crown - Chapter Two**

* * *

Nearly a week later, she watches Lily retreat into the office after dinner, citing something she _has_ to work on before they watch their movie. A glance back at Castle tells her he has no idea what their daughter is up to either, but instead of going after her, Kate sneaks a kiss from Reece before lifting Jake into a football carry.

Her son giggles, clutching at her shirt. "Mama, let's pway!"

"Play?" she gasps. "Are you sure you want to play?" She waits for them to confirm, pretends to think about it. "Okay then, what are we playing?"

Jake cackles, locking eyes with his brother. As often as she and Castle have shared their thoughts without a word, it's still uncanny how the boys communicate. "Dinos!"

"Dinos," Kate echoes, hefting Jake and reaching for Reece as well. Her back cringes with the effort it takes to hang onto them both, tugging at the long-healed scar on her abdomen, but she doesn't release them. Old wounds won't stop her from keeping her babies close. "Okay, my raptors, let's play dinos until Daddy's done with the dishes."

Rick laughs from his spot at the counter. "I see how it is."

"Would you rather be the climbing wall?" She lifts an eyebrow, hauling Jake higher up her body. She had the day off, which meant the boys have been stuck to her for most of the day, but typically Rick bears the brunt of their sons' roughhousing.

"Anything else you need washed?" her husband asks, making his answer clear.

Kate laughs, shaking her head. "No, babe. I think you have everything. Unless you want to wash Peanut Butter and Jelly in the sink the way we used to."

Both boys cackle, shouting that sinks aren't for baths.

"They were when you were first born," she singsongs, swaying with her sons. "You were so little, we gave you all of your baths in the sink until you got big enough for your bath chairs."

"Nooo."

"Yeesss," she says as she moves to the couch to flop down with them. "But not anymore. You get regular baths now. Like all little raptors."

They make dinosaur screeches in return, happily scrambling from her arms to hop beside her on the cushions. Seconds later, they're climbing around her shoulders, squealing when she pretends to be a Tyrannosaurus Rex out to get them.

Rick laughs from the kitchen, calling out a reminder for the boys to be careful.

"Remember the last time you raptors launched an attack on the T-Rex."

Kate narrows her eyes, looping her arms around the twins to keep them in place and unable to pitch forward as she twists to face her husband.

"What happened last time?" she asks, watching Rick busy himself at the sink again. "Castle?"

"Cassle, Cassle, Cassle," the boys chant, giggling at their own cleverness. Ever the parrots.

"There… may have been an unintentional flip or two. But they stuck the landings."

She shouldn't chuckle, but she does. She has to laugh, otherwise she might try to wrap her kids in bubble wrap and never let them go. "Of course they did. But guys, you've got to be careful," she adds, turning back to face the boys, giving them a brief, firm squeeze.

"I'll be so caweful," Reece assures, touching her cheek in what she has to accept as a non-binding promise. "Jakey, too."

Kate grins, dusting a kiss to his little hand. "Thank you, sweet boys. I know you will."

At least for the next four and a half minutes, if that long.

They giggle together taking turns smacking kisses on her cheek, buttering her up just like their father does.

"Okay, raptors," Castle calls a few minutes later, wiping his hands on a towel, "come pick your dino snack. Let's get this movie night started."

"I'll grab Lily," Kate says, getting to her feet, blowing a raspberry on Jake's neck before he can squirm away.

Castle laughs, already situating stools for the boys to climb to reach the counter. Kate offers an affectionate smile over her shoulder as she navigates the chaos of the living room, tapping on the bookshelf to signal her approach.

Lily jolts despite the warning, slapping her hand down on the desk, covering whatever she's doing with her palm.

Well that reaction is interesting. It's certainly an escalation from the last time she'd found the girl in the office like this.

"Momma! Hi!"

Kate tilts her head. "Hey, baby. We're almost ready to watch the movie, but Daddy wants us to pick our snacks first. Wanna come do that?"

She's been both a cop and a mom long enough to spot the evasion techniques – the way Lily's eyes flick down to her hand and then out to the living room, but she doesn't draw attention to it yet.

"Can I have five more minutes? Please?"

Kate nods, watching Lily's shoulders sag in relief. "Want me to pick your snacks for you? Then all you need to do is come watch?"

Her daughter brightens. "Uh huh! M&Ms and gummies."

Kate nods, smothering a smile. How alike they are; she and Lily ask for the same thing nearly every time. "On it, little flower. See you in a few minutes, okay?"

"Thanks, Mommy." Lily's back at work before Kate can reply, her face the picture of concentration.

Patting Branko on the head, Kate slips from the office without a sound. Rick lifts an eyebrow when she joins him at the counter without company.

"Where's Lil?"

"She's finishing up," she hums, dragging her fingers along his back on her way around him, delighting in the tiny shiver that rolls up his spine. "Told her I'd get her snacks and she can meet us on the couch."

"Ahh. What's she working on?"

Kate lifts a shoulder. "No idea; she covered the paper as soon as I walked in."

Castle's lips spread. "Ooh, a secret. Oh, maybe she's already starting to plot world domination."

She laughs, nudging him away from the popcorn with her elbow. "I think it's far more likely that it's something personal; she might be journaling. I remember I started writing in a diary around that age."

"Spoilsport," he quips without missing a beat. "She would make a great world conqueror, though. She's cute enough that nobody would ever expect it, but then she'd put her hands on her hips and narrow her eyes the way you do – yeah, like that – and they'd be toast."

"And yet my narrowed eyes never seem to work on you anymore," Kate teases, tilting her head. Abandoning the treats she's divvying up, she winds her arms around her husband's waist, swiping her lips across his chin.

Rick chuckles. "I've built up my defenses. It's one of the many benefits of our extreme familiarity."

"Is that what the kids are calling it these days?" She steals a kiss, nipping at his lower lip. "Extreme familiarity?"

"Eh. Either way, it's never boring," he says, cupping the wings of her shoulders. She laughs, conceding that point. This life of theirs is the furthest thing from dull, and she wouldn't change a second of it.

"Mama, Daddy, no more kissing," Jake whines over the back of the couch. "It's movie time now."

Reece echoes his brother's sentiment, taking great care to flop onto the cushion behind him in a show of exasperation. Kate grins, sneaking one last kiss from her husband's mouth before reaching for two bowls and stepping away from the counter.

"So dramatic, just like your daddy," she teases, striding into the living room to join her little boys.

Reece giggles, squirming under her arm to steal an M&M from his sister's snack bowl.

"Chew," Kate instructs, pulling him back to keep him still. The last thing they need is for the evening to include the Heimlich. "You, too," she adds, narrowing her eyes at her husband when he flops beside her, his cheeks already full of snack food.

Jake chortles, rocking into Rick's side. "Daddy's a chipmunk!"

"Daddy's something," she drawls, nudging her husband's knee with hers, offering him a lazy smile.

Branko emerges from the office ahead of Lily just as Rick hits play on the DVD.

"There she is," Rick rumbles, scooting just enough for their girl to squeeze between them while the dog curls up at their feet. "Did you get your work done?"

Lily nods, taking her bowl from Kate with murmured gratitude. "What are we watching?" she asks, poking Reece's little knee.

Reece giggles, pressing the pad of his index finger to her nose in return. "Minions."

"No," Kate says, quick to cut that one off at the pass. If she never sees one of those damn minions again, it'll be too soon. "No minions tonight, Peanut Butter. We're watching Daddy's pick this time. It's his favorite."

"One of them," Rick adds, dropping a kiss on Jake's head. "I have many."

Lily giggles, reaching across her brother to pat Rick's arm. "Me too, Daddy. It's hard ta pick just one."

Rick grins at the display of solidarity. "That's exactly it, Sprout. I knew you'd understand."

Kate smiles, brushing her fingers over her daughter's hair, holding her kids close as the movie begins.

Later, after the kids are in bed and her husband is taking care of his nightly routine, she makes a detour into the office, checking her desk to be sure the file she needs for her first meeting is where it needs to be. The file sits in the center of the blotter, exactly where she'd left it after looking over it earlier, but it's underneath a folded piece of familiar stationery. Smothering a smile, she chances a glance at the paper, hoping she's not spoiling a surprise for the morning.

Instead of one of Lily's adorable, carefully printed, good luck notes, Kate finds herself staring at what looks to be gibberish, a jumble of letters and numbers. Confusion mars her brow, only to disappear a moment later as she remembers Lily's excitement the other night, the book about the princess who saved the prince by using the right cipher.

She grins, half in amazement, half in anticipation. Her daughter has left her a code to crack. Not Castle, the man who's up for any type of game (though he's less fond of spies now than he used to be), the man who brings make-believe to life every day. No, Lily left it for her.

She's going to make sure she solves it. Tonight.

* * *

The code looks to be short, just a few sentences, but it still takes her a moment (and a long look at a book of codes that she finds stashed on the shelf her daughter had used the other day) to understand the pattern. Lily's chosen the tried and true method of switching the alphabet so z equals a, y equals b, and so on, and Kate's even more impressed when she realizes that numbers have been substituted for punctuation as well.

Her eyes are gritty by the time she transposes the final letter of Lily's note, but her pride keeps her from calling it a night just yet. She's the one Lily wanted to share her code with; she wants to bask in that for a little longer.

 _Dear Queen, the king and his princes need our help. If you are brave, say so with the words 'dancing purple people eater,' and our quest will begin. But be careful! Regular notes can be read by anyone, you must keep ours secret to save the royal family._

Well, if that's not a hint to respond in code, she doesn't know what is.

She decides to take things one step further in answering Lily's letter, changing the key just enough to offer her daughter a challenge decoding her response. After that, she pens a note of her own, asking for more instructions and providing further 'intel' to put toward their quest. If she finishes tonight, she'll be able to leave it for the girl to tackle tomorrow.

"Kate?"

She looks up from her paper almost an hour later, glancing around the room before her eyes land on her husband leaning against the bookshelf in the doorway to their bedroom.

"You coming to bed?" he asks, amused. "Unless… did work call?"

Shaking her head, Kate gestures to the page in front of her. "Not work. Lily left me something and I just want to finish this so I can give it to her in the morning, then I'll be there."

Castle straightens, his interest piqued enough to wash away some of his sleepiness.

"Come see," she beckons, dangling the letter from her fingertips.

He lumbers over, arm stretched out to take the paper from her hand. She watches his brow furrow for a split second before he gets it.

"She wrote you a code?" he squeaks. "I _love_ codes. Have you already solved it? What'd she say? What was her cipher?"

Hooking her fingertips in the waistband of his pajama pants, Kate stills him and silences his questions. "Mhmm. Cracked the code a little while ago." She holds out the translation. "Check it out, be proud."

"Of the two of you? Always," he rumbles, dipping to press his lips to hers. Kate grins into the kiss, pleased by the praise no matter how corny it is.

"Uh huh," she teases anyway, rubbing his hip. "Read what she wrote."

He does, smiling in affection for their little girl. "That's adorable."

"Isn't it? So how do you think the king and princes will be saved? Think she's about to start making a case for another dog?"

Her husband laughs, hearty and warm. "No, Kate. I think she just loves you and wants to share her fun with you. Or she's about to start making her case for a cat. I heard her asking Alexis about Tiger the other day."

She grins, leaning into him a little more. "Yeah, Branko would love that."

Rick's lips twitch in amusement. "Another tiny thing for him to protect? Branko the nanny dog would be over the moon. He'd never let a kitten out of his sight."

He has a point there. Kate chuckles, shaking her head. "We're not getting her a cat, too."

"Until she asks," Castle adds, dodging her swatting hand. "I'm just saying, let's not say never. After all, you once said that about me. And look where we are now."

She purses her lips to hide a smile. He has a point there, too. But he's not going to convince her to add another pet to their crazy life on the off-chance that it's what Lily wants.

"Go to bed, you troublemaker," she murmurs, nudging him back. "I'll be there in a few minutes, I just want to finish this for her."

Rick grins, pressing a kiss to her hair. "Take your time. Secret codes can't be rushed," he says before slipping away.

Dragging her teeth over her lip, she wonders if she should've invited him to stay and play cryptologist with her, but he doesn't seem offended or snubbed. If anything, he seems content to let this be her thing with Lily.

Still, when she pads into her bedroom and crawls beneath the comforter a little while later, she takes great care to press herself to his side and offer him some special attention, too.

She goes to work tired, but it's worth it.


	3. Chapter 3

**Codes and the Crown - Chapter Three**

* * *

The letters continue over the course of the next few weeks, growing longer and more complicated as their adventure builds. Every few days, Lily tweaks the cipher, dropping clues as to the changes she's made, but saying nothing more than that. Each time she receives a new message, Kate does her best to crack the code and respond – complete with her own challenge, of course – before she heads to bed, but there are some evenings when she's just not able to; nights when she works late and is too exhausted to think about secret codes once she finally makes her way home, or when she just needs to spend the time holding her kids or resting with her ear pressed to the steady beat of her husband's heart instead of burning the midnight oil in the office. She thinks Lily understands the occasional delay, but she still does her best not to disappoint the girl, going as far as to bring the notes and Lily's book of codes to the precinct with her to pour over on her lunch break when it feels like too many days have passed since they exchanged their last message.

The second time that happens, she makes sure to hide the note in their agreed upon drop box when she gets home, pretending not to watch her daughter duck into the office between dinner and breaking out the board games. Lily returns a few minutes later, kissing Kate's cheek and leaning into her arm.

Kate lifts a hand to keep the girl close, turning her face to hide a smile in her daughter's temple. "Ready to kick some butt at Scrabble, little flower?"

Lily nods, her grin bright. She slides a leg over Kate's, climbing into her lap. Kate wraps an arm around the girl's waist once she's settled, pressing her cheek to her daughter's.

"Okay, Castle, get ready to lose," she teases, watching her husband's eyes flare. He's gotten better about his propensity for sulking whenever he's defeated at – as he says – a wordsmith's game, but his competitive spirit hasn't faded. Even when they play with their daughter, he takes it seriously.

"You're on," he rumbles, sneaking a kiss from Lily first, then coming for her. "But just for that, the boys are on my team."

Kate grins against his lips. The boys are sacked out on the couch, their mouths half-open and their hair wild from the odd ways they're sprawled.

"Crack team you've got there," she hums, wiggling her eyebrows. Lily giggles from her arms, rubbing her palms together with glee.

"Daddy's going down," her daughter announces. Kate echoes the sentiment, brushing her foot against Rick's as they get the game started.

There's another note waiting for her in their drop box when she gets home the next night. Except for Branislav, her entire family is at a movie with Alexis, so she dives in, ready to tackle Lily's most recent communication. Even though Lily's cipher has grown in complexity, Kate's able to follow along. At least until the message she has translated just doesn't make _sense_.

She tries again, starting from scratch and using Lily's book as a guide to make sure she hasn't made a mistake somewhere. It comes out the same, a puzzling phrase that makes her brow furrow.

"Is this another code," she asks Branko after she's spent almost ten minutes studying the message, "or are we going to have to work on her spelling some more?"

Branislav stands, stretching his back before circling the desk to rest his head on her leg. Rubbing her hand over his ears and down his back, Kate takes a deep breath. Branko's been so good for them, their sweet boy since the day just a few months after Lily's first birthday when Castle had found him on the street and brought him home, and just the act of stroking his fur helps clear her mind.

"Okay, Branko. Let's go for a walk and then we'll come back to this."

He seems more than happy to accompany her for a few blocks before they turn around and head home, sticking close to her side as they stroll down the sidewalk. By the time they make it back to the loft, she has concluded that there is no secondary code, it's just an unfortunate error in spelling that's tripping her up. After all, Lily's still shy of seven; it's impressive that she's been as good as she has.

With that mystery solved, she takes her seat again, rubbing Branko's head when he makes himself comfortable beside her, and gets to work using the context of the rest of the message to understand that they're arranging a meeting by a particular tree in their fantasy forest. She's just finishing up her reply when the front door clatters open, and pats herself on the back for the timing.

"Momma, we're back! Lexi came too, and we brought ice cream!" Lily calls, lowering her voice a second later to add, "Oops. Sorry, Peanut Butter. Sorry Jelly."

Kate laughs into her hand, watching the dog get to his feet. He's so very eager to get to his girl, he doesn't even look back as he trots through the doorway, leaving Kate to make her way from the office on her own.

"Hey, Alexis," she says, offering the redhead a smile. "Did he fall asleep on you?" she asks, noticing Jake's dark head on his eldest sister's shoulder.

"Hi, Kate. He's almost there," she murmurs, twisting so Kate can see Jake's heavy-lidded eyes. "Reece is, too. Dad has him."

Kate nods, dipping her head to kiss Lily hello before doing the same for the others. She lingers at Rick's side, allowing him to steal a second kiss and swiping a hand up his back. "Did I hear something about ice cream?" she asks after a second, watching her daughter light up.

"Uh huh!" Lily says. "We got _so_ much, and then PB and J started falling asleep, so I dunno if they're going to eat it."

"We'll save them a little and eat the rest," Alexis assures, offering her sister an exaggerated wink. "In fact, Kate, why don't I give you Jake, and Lily and I will get everything set up while you and Dad put the boys to bed?"

Kate nods, stepping closer to lift her son from his sister's arms. "We'll be down in a few minutes," she promises, tapping Lily's nose. "Don't eat all the ice cream, little flower; I want my portion."

Her daughter grins, skipping into the kitchen. "Nah uh, I'm going to eat it all!"

Kate laughs, shaking her head. "I'll get you if you do."

She starts to mention the office and the letter that's waiting for her daughter on the desk, but stops herself. No doubt Lily will duck in there on her own at some point; she won't ruin the intrigue – or burst the bubble of imagination – by calling attention to the game.

Sure enough, as she makes the turn at the top of the stairs, Kate looks back to see Lily darting between the bookshelves, Branko on the girl's heels.

* * *

It's bittersweet the day the king and princes are saved and their quest comes to an end. They've spent the better part of the summer cocooned in a world of their own creation, a world where an intrepid princess from a distant land and a queen-turned-closest advisor can save a kingdom, and the thought of it being over is enough to send a pang through her. She and Lily might not talk about their codes, but it's been something that's theirs and theirs alone, and Kate's not sure she's ready to give that up.

So when she decodes Lily's final message, a letter of congratulations and commendation for her bravery, Kate decides it won't be the end. There are ways to keep the fun going; it will take work, but she'll make it happen to keep the smile on her daughter's face.

On Lily's first day of school, Kate slips a coded message wishing her well from a grateful kingdom into her daughter's lunch box. The next day, she finds a new cipher tucked into her briefcase as she settles into a briefing.

She doesn't decrypt it during the meeting, but the code certainly occupies her thoughts – and the notes she makes on her legal pad. She makes quick work of it once she returns to the precinct from 1PP, giving the bullpen a cursory glance before rereading her daughter's sweet reply.

 _Queens, princesses, and protectors of the kingdom always stick together. Even when they're on other quests._

The code and its translation goes into the top drawer of her desk for safekeeping, where it stays until she turns off her computer and begins to pack up for the evening.

Her home is anything but silent when she steps into the loft a little while later. Her sons scramble down from the couch (by way of the pile of pillows on the floor, of course), their socks slipping on the hardwood in their haste to get to her.

"Mama!" they call as one. Sort of.

"Hi boys," Kate says, steadying them with sure hands, pressing kisses to their cheeks. "You look like you're having fun. Did you have a good day?"

They beam, barely stopping to take a breath as they tell her everything they'd done in preschool that day. When Jake trails off, Reece picks up, adding bits and pieces to the story until she's up to speed.

"Well it sounds like you had fun," Kate murmurs. "I can't wait to see your art. I'll go find your backpacks once I change my clothes." They giggle and squirm until she releases them to continue their game.

"Their bags are over here," Rick calls, waving from the table by the window where he sits with Lily. Kate grins, getting to her feet again, eager to greet her daughter and her husband.

"Homework?" she asks, stepping between them at the table. Her arm winds around Lily's shoulders, drawing her daughter into an embrace.

Lily nods, wrapping her arms around Kate's waist. "Math today," she explains, gesturing to the papers spread on the table in front of them. "Daddy's helping me."

"She's just humoring me; she doesn't even need my help," Rick boasts, getting to his feet, impatient for his own greeting.

Not that Kate blames him. With the kids back in school, she'd been looking forward to having him come into work with her for a few hours, but they both know there's no point to it on days when she goes downtown. Tomorrow, though, he'll be back with her and she can't wait even a bit.

Beckett grins, patting his chest and leaning into his kiss. "She's a smarty, babe."

Castle chuckles upon retreating to his seat. "That she is. How was 1PP today?"

"Good. Gates says hello," Kate says, rubbing Lily's shoulder. "She wanted me to wish you luck at school this year."

Lily nods, pressing her cheek to the lapel of Kate's blazer. Her daughter loves everyone in their NYPD family, but Gates has always been special to the girl. "Thanks."

She hums, dotting a kiss on her daughter's head. "What do you guys want for dinner? I'll get it started in a minute or two."

Rick's fingers tap her arm drawing her attention back to him. "I picked up some chicken at the store earlier," he says. "The boys were begging for mac and cheese, but I convinced them to wait until Friday, so I figured we'd liven up some veggies tonight and treat ourselves at the end of the week."

"Stir fry?" she offers, cocking her head in thought. "We should have everything for that, right?"

He nods, glancing sideways at the boys. Kate breathes a sigh of relief when she follows his gaze and finds her sons have abandoned roughhousing on the couch in favor of roughhousing on the floor. "They'll eat it."

"What about the rice, Momma? Can you make that? It's so good when you make it. Please?" Lily asks, looking so hopeful Kate knows she's going to agree. It's not that much extra work to make fried rice, after all, and her kids _do_ love it.

She nods, thumbing Lily's arm through her shirt. "Sure, little flower. Chicken stir fry and fried rice for dinner."

Her daughter beams. "Can I help?"

"After you finish your homework. Then I'll put you to work." She kisses Lily's head, releasing her a second later.

"What about me?" Rick asks, his smile in his eyes. "Once we're done with homework, of course."

"You relax," she murmurs, looping her arms around his neck, using the kiss she steals as an excuse to whisper, "I have plans for you later." She squeezes him, stepping away before he's able to drag her back in and convince her to give him a preview of those plans.

Lily joins her in the kitchen a few minutes later. "Daddy checked my paper – I got everything right."

Kate grins, dropping a kiss on her head. "I knew you would. Now, what would you like to do? Measure our spices and pour them in when we need them, or stir the chicken and the veggies once I put them in the wok?"

Lily taps her lips in thought. "The spices. I like that job."

"Perfect." Beckett pulls a stool over, pats it in invitation.

Lily climbs up, bouncing in her excitement to help, taking the measuring cup Kate offers her without a sound.

They make a good team; Lily's careful with the ingredients, meticulous in her measurements, and unfailingly eager to taste test to make sure nothing is going awry in the process. Once everything is in the wok, they take turns stirring, sharing grins when Rick attempts to swoop in to sneak a taste of the rice for himself.

"Daddy, just wait," Lily instructs, gesturing with her wooden spoon.

"Yeah, Daddy," Kate teases. Snagging him by the waist, her fingers lace at the small of his back and she pulls him in close. "Just wait."

He slips an arm around her in return, brushes his thumb against her shoulder blades. "But I'm hungry."

"Oh, you poor thing." Her lips brush his, tasting his smile. "I think you'll survive waiting another five minutes until dinner."

"Yeah, Daddy, it's just five minutes," Lily parrots, beaming at Kate's answering laugh. "You'll survive. We promise."

"It's not anywhere near fair that you two team up against me, you know," Rick says, though there isn't a trace of displeasure in his voice.

"What else would we do?" she asks, thinking about a summer spent growing closer to her kid. Lily's message from earlier in the day flashes in her mind, and the truth in her daughter's words warms her veins. "We've got to stick together after all."

* * *

 _Thank you all so much for your wonderful, kind words on this story! Only the epilogue to go._


	4. Chapter 4

**Codes and the Crown - Epilogue**

* * *

"Hey, Mom? Mom?"

Kate blinks, turning away from the hypnotic twinkle of the lights on the Christmas tree to find her daughter waiting by the couch, the cat circling her legs. Lily tilts her head, smiling quickly before she speaks again,

"Sorry, I didn't mean to startle you. I thought you heard me come down."

"You didn't," Kate murmurs, flexing her fingers around her now-cold mug, glancing at her feet to find Branko still sacked out beside her. He doesn't attempt the stairs anymore, which saddens the kids and Zosia, but he's a good companion for Kate on late nights like this, when she doesn't want to wake Rick. "I just spaced out looking at the lights. What's up?"

Lily bites her lip, shifting her weight on her bare feet. "Can I sit with you?" she asks, sounding so young, so much like the little girl she used to be instead of the bright-eyed college freshman she is, it steals Kate's breath.

"Of course, little flower. You don't need to ask."

Her daughter grins, almost to herself, closing the distance between them without a word. Kate opens the blanket to her as soon as her knee hits the couch, and despite the long sleeve shirt and fleece pants the girl wears, Lily slips underneath the throw, tucking herself close. Zosia follows a moment later, hopping onto the back of the couch and taking her preferred spot at Lily's shoulder.

"What's on your mind, sweetheart?" Kate asks once they're settled, brushing her hand along Lily's arm. They'd all retired to bed early – except for Jake, of course, whose video game she'd heard blasting until just a little while ago – but sleep seems to be evading at least part of the house.

Lily lifts a shoulder. "Just stuff. Lots of stuff."

"School?" she tries, not wanting to interrogate her daughter, but not wanting to let something fester if Lily needs help expressing it. It's how her mom had approached things, too.

"Kinda. I keep thinking about this past semester. What if I didn't do as well as I think I did? What if I lose my scholarship? What if I get kicked out–"

"You won't," Kate soothes, touching her fingertips to Lily's temple. "You did great, and the classes you maybe didn't do great in, you did enough. That's what matters."

Her kid nods, releasing a sigh.

"I declared my major last week."

Kate smiles. "Yeah? Like we talked about?"

Lily exhales. "Yeah, and it felt right at the time, but now all I can think is that maybe I've made a mistake and I'll hate my classes, and I should take it back and wait a little longer. And I don't even know if you _can_ undeclare, and I just–"

"Baby, breathe," she murmurs, cupping her daughter's cheek, getting her eyes. "You are going to be amazing in the math department. But if you get a couple of classes in and you realize you hate it? You can change to something else. Something you find more interesting, something you have a greater passion for, whatever you want. Until the ink is dry on your diploma, nothing is set in stone."

Her daughter blinks, sucking in a deep breath that Kate helps her release.

"College is hard," she continues once Lily looks a little less panicked. "It's not going to be smooth sailing all the time, but you'll get through it. And you'll be okay. And Dad, the boys, and I will be here for you the whole way."

"Thanks, Momma," Lily murmurs, knocking her forehead on Kate's shoulder. Kate holds her tighter, remembering having a similar conversation with her own mother that first Christmas break after she'd started at Stanford. The last Christmas she'd had with Johanna.

"What else?" she asks, diverting her attention from her memories back to her own kid. "What else is on your mind, I mean?"

Lily curls closer, looking around the loft, taking in the snowflakes hanging from the ceiling, the garland and the lights. The house doesn't look the same as it has in previous years – with Alexis across the country, Lily at school in New Jersey, and the boys rather apathetic to Christmas cheer, decorating had fallen on Kate and Rick, which meant it's been done piecemeal over the course of the month instead of in one fell swoop the way it used to be. But it's still good; it's still joyous and warm, everything they've needed with their lives being so crazy right now.

"Can I give you one of your presents now?" her daughter asks.

Maybe that's what she'd intended to say and maybe it isn't, but Kate nods nonetheless.

"Sure, honey. We won't tell your dad that we're breaking the time-honored tradition of presents on Christmas Eve night, though," she murmurs.

"Probably for the best," Lily says on a quiet laugh. "What Daddy doesn't know won't hurt him this time."

Kate chuckles, sneaking a glance into the office anyway. Rick had been sprawled out on his back in their bed when she slipped from beneath the covers, but there's no telling if he's still passed out. She hopes he is, and not just because this feels like a moment for just girls. He's been working so hard these last few weeks, finishing his next book, helping her with her campaign, trying to keep up with the boys and take care of Martha, not to mention distracting her from getting mired in the melancholy of the holidays that never really goes away; he needs the sleep.

"You're right," she agrees, turning to watch Lily scamper across the living room to dig a neatly wrapped gift out from behind the Christmas tree. Tossing the blanket aside, she joins the girl at the tree, lifting a smaller present to give in return.

"Okay," Lily breathes once they're seated again (having made a quick detour to love on Branko first), pushing her hair behind her ear. "Ready?"

"Ready."

They trade gifts, digging into the wrapping with childlike glee. Kate pauses for a moment, watching Lily's face as she opens the box to reveal the alexandrite pendant.

"Mom, it's so pretty," Lily breathes, touching the coil of wire that cradles the stone. "Is it handmade?"

Kate's lips lift. "Yeah it is. I saw it a few weeks ago when Dad and I were wandering a craft fair in the Hamptons, and I thought you'd like it."

Lily's head bobs as she surges forward, wrapping an arm around Kate's shoulders, whispering her gratitude. "I do. I love it, thank you."

Kate holds her tighter, swiping a hand up her back. "I'm glad, baby. I'm so glad."

Her daughter squeezes her once before settling back, leaning her cheek on Kate's shoulder. "Your turn. Finish opening yours."

Her fingers flutter at the edge of the gift, tearing at the wrapping paper to reveal a hardback book.

 _Codes and the Crown: How Spycraft Saved the Queen_

Her heart swells, remembering a summer of ciphers and quests to save the royal family, coded messages in lunchboxes and tucked into case notes. It had been something that was purely theirs, hers and Lily's, and she's never allowed the memories to slip far from the front of her mind.

"Do you remember?" Lily asks as Kate opens the cover to find her daughter's familiar handwriting dedicating the book to her, co-protector of the crown, queen to her grateful princess.

"Our codes," Kate confirms, turning her face into her daughter's hair. "I still have them all. Some here, some in my desk at work."

"Me too. They're in my special stuff drawer upstairs." Lily squeezes her again, drawing herself closer. "I'd forgotten all about them until I saw the book in Barnes and Noble one day. Gonna admit, I read it before I got it for you; it's good. I was afraid it might be dry, but it's good. I really think you'll like it, Mom."

Kate brushes her fingertips over her daughter's cheek, drawing her closer. "I love it. Thank you."

Lily dips her head, leaning into the affection. "Thank you for playing along the way you did. I know it was probably a pain in the butt at times, but you still did it."

As if she would've done anything else, especially knowing how invested Lily had been in seeing the game through to the end.

"You don't have to thank me for that," she murmurs, touching her fingers to the dust jacket. "I had fun, even when it was tough. Most of the time when I was stressing, it was because I wanted to get it done so you could have your turn again. But I'd do it all over again for you. And for the kingdom."

"Me too." Her daughter grins, shifting on the couch as Kate opens the book to read the introduction. She closes the book after a couple of pages, vowing to settle in to read the rest another time.

Kate's not surprised when there's a new cipher waiting in her stocking on Christmas morning, and she's also not surprised when she has to convince herself to finish opening the rest of her presents before she can jump into cracking it.

To his credit, Castle doesn't blink an eye at her distraction once all the gifts have been unwrapped. Instead he convinces the boys to break out their new game system and start playing.

Unlike the first time she and Lily played this game, though, they don't worry about working in secret. This time as Kate works to decrypt her daughter's message (which is arguably more sophisticated this time around), Lily is right beside her, grinning into her hand, eagerly awaiting her reply.

There's no time to waste, after all; they have a kingdom to defend.

* * *

 _And that's a wrap for this tale! This story was inspired by a tumblr post (_ _bunysliper. tumblr post/157547063573/unicornempire-justastormie )_ _and then prompted as a fic by a super sweet Anon. Thank you so much! I hope you liked it._

 _Thank you all for reading! Until next time._


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